diff --git a/.github/workflows/test-models.yml b/.github/workflows/test-models.yml
index c79f72da..dc9508b5 100644
--- a/.github/workflows/test-models.yml
+++ b/.github/workflows/test-models.yml
@@ -5,11 +5,13 @@ on:
     branches:
       - master
   pull_request:
-    branches:
-      - master
+    branches: ["*"]
   schedule:
     - cron: "0 5 * * *"
 
+env:
+  PACKAGE_NAME: "linopy"
+
 # Cancel any in-progress runs when a new run is triggered
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
@@ -24,13 +26,24 @@ jobs:
       matrix:
         version:
           - master
-        # - latest # Activate when v0.14.0 is released
+        # - latest
 
     defaults:
       run:
         shell: bash -l {0}
 
     steps:
+      - name: Free up disk space
+        run: |
+          echo "Initial disk space"
+          df -h
+          echo "Free up disk space"
+          sudo rm -rf /usr/share/dotnet /usr/local/lib/android /opt/ghc /opt/hostedtoolcache/CodeQL
+          sudo docker image prune --all --force
+          sudo docker builder prune -a --force
+          echo "Final disk space"
+          df -h
+
       - uses: actions/checkout@v5
         with:
           repository: PyPSA/pypsa-eur
@@ -43,6 +56,18 @@ jobs:
           latest_tag=$(git describe --tags `git rev-list --tags --max-count=1`)
           git checkout $latest_tag
 
+      - name: Setup Pixi
+        uses: prefix-dev/setup-pixi@v0.9.3
+        with:
+          pixi-version: v0.59.0
+          cache: true
+          # Do not cache in branches
+          cache-write: ${{ github.event_name == 'push' && github.ref_name == 'main' }}
+
+      - name: Setup cache keys
+        run: |
+          echo "WEEK=$(date +'%Y%U')" >> $GITHUB_ENV # data and cutouts
+
       # Only run check if package is not pinned
       - name: Check if inhouse package is pinned
         run: |
@@ -53,51 +78,29 @@ jobs:
               echo "pinned=false" >> $GITHUB_ENV
           fi
 
-      - name: Setup secrets & cache dates
-        if: env.pinned == 'false'
-        run: |
-          echo -ne "url: ${CDSAPI_URL}\nkey: ${CDSAPI_TOKEN}\n" > ~/.cdsapirc
-          echo "week=$(date +'%Y%U')" >> $GITHUB_ENV # data and cutouts
-
       - uses: actions/cache@v4
         if: env.pinned == 'false'
         with:
           path: |
             data
             cutouts
-          key: data-cutouts-${{ env.week }}
-
-      - uses: conda-incubator/setup-miniconda@v3
-        if: env.pinned == 'false'
-        with:
-          activate-environment: pypsa-eur
-
-      - name: Cache Conda env
-        if: env.pinned == 'false'
-        uses: actions/cache@v4
-        with:
-          path: ${{ env.CONDA }}/envs
-          key: conda-pypsa-eur-${{ env.week }}-${{ hashFiles('envs/linux-64.lock.yaml') }}
-        id: cache-env
-
-      - name: Update environment
-        if: env.pinned == 'false' && steps.cache-env.outputs.cache-hit != 'true'
-        run: conda env update -n pypsa-eur -f envs/linux-64.lock.yaml
+          key: data-cutouts-pypsa-eur-${{ env.WEEK }}
 
       - name: Install package from ref
         if: env.pinned == 'false'
         run: |
-          python -m pip install git+https://github.com/${{ github.repository }}@${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
+          pixi remove ${{ env.PACKAGE_NAME }}
+          pixi add --pypi --git https://github.com/${{ github.repository }}.git ${{ github.event.repository.name }} --rev ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
 
       - name: Run snakemake test workflows
         if: env.pinned == 'false'
         run: |
-          make test
+          pixi run integration-tests
 
       - name: Run unit tests
         if: env.pinned == 'false'
         run: |
-          make unit-test
+          pixi run unit-tests
 
       - name: Upload artifacts
         if: env.pinned == 'false'
@@ -109,3 +112,7 @@ jobs:
             .snakemake/log
             results
           retention-days: 3
+
+      - name: Show remaining disk space
+        if: always()
+        run: df -h